What are the diagnostic criteria for rhabdomyolysis?

From the Guidelines

Rhabdomyolysis is diagnosed based on elevated serum creatine kinase (CK) levels typically greater than 5 times the upper limit of normal (often exceeding 1,000 IU/L), myalgia or muscle weakness, and myoglobinuria resulting in dark, tea-colored urine. The diagnostic criteria for rhabdomyolysis include:

• Elevated serum CK levels, with levels above 75,000 IU/L associated with a high incidence of acute kidney injury 1
• Myoglobinuria, which can be detected by urine dipstick testing and is responsible for intraluminal kidney tubular obstruction resulting in reduced glomerular filtration rate 1
• Elevated serum creatinine, hyperkalemia, hypocalcemia, hyperphosphatemia, hyperuricemia, and metabolic acidosis
• Laboratory tests should include a complete blood count, comprehensive metabolic panel, urinalysis, and serum CK levels 1
• Repeated bio-assessment combining plasma myoglobin, plasma creatine phosphokinase (CPK) and kalaemia measurements, as well as bladder catheterisation to monitor hourly urine output and urine pH, which should be maintained at 6.5 1 The diagnosis of rhabdomyolysis requires a thorough history to identify potential causes such as trauma, excessive exercise, medications (particularly statins), infections, or metabolic disorders. Early diagnosis is crucial as rhabdomyolysis can lead to acute kidney injury, compartment syndrome, and electrolyte abnormalities. Treatment should begin immediately with aggressive intravenous fluid resuscitation using normal saline at 1-2 L/hour initially, then adjusted based on urine output, with a goal of maintaining urine output at 200-300 mL/hour until CK levels decrease significantly.

From the Research

Diagnostic Criteria for Rhabdomyolysis

The diagnostic criteria for rhabdomyolysis include:

• Elevation of serum creatine kinase activity of at least 10 times the upper limit of normal, followed by a rapid decrease of the serum creatine kinase level to near normal values 2
• Elevated creatine kinase levels, with additional testing needed to evaluate for potential causes, electrolyte abnormalities, and acute kidney injury (AKI) 3
• Elevated creatine phosphokinase (CPK) of at least 5 times the upper limit of normal, although CPK alone may not be a sensitive marker for rhabdomyolysis-induced AKI in some cases 4
• Serum creatine kinase greater than five times upper limit normal, which is a common definition used in clinical settings 5
• A substantial rise in serum creatine kinase (CK) >50 000 IU/L, combined with symptoms such as myalgia, weakness, and muscle swelling, in the case of exertional rhabdomyolysis 6

Clinical Presentation

The clinical presentation of rhabdomyolysis can vary widely, with classical features including:

• Myalgia
• Weakness
• Pigmenturia However, this classic triad is seen in less than 10% of patients 2

Complications

Rhabdomyolysis can lead to several complications, including:

• Acute renal failure due to acute tubular necrosis as a result of mechanical obstruction by myoglobin 2
• Hyperkalemia
• Compartment syndrome These complications must be treated effectively to prevent serious consequences 3